An Intermediate Mass Black Hole Found in the Milky Way. 100,000 Times the Mass of the Sun

Astronomers have been searching for mid-weight black holes, and now they’ve found one, right here in the Milky Way.

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Team: Fraser Cain - @fcain / [email protected]
Karla Thompson - @karlaii / https://www.youtube.com/channel/UCEIt...
Chad Weber - [email protected]
Chloe Cain - Instagram: @chloegwen2001

I can’t believe my luck. Just last week as we were putting up our newest video about how smaller black holes combine into more and more massive black holes, leading up to supermassive black holes, astronomers announced one of the most important discoveries in black hole research in the last few years.

So, as I sometimes do, I’ve stopped the explainer video train to report on a very important piece of space news. And actually cover a topic that I’ve had in my queue for a while: the search for intermediate mass black holes.

Half news, half explainer. Enjoy.

Astronomers from Japan announced last week that they had discovered a black hole with 100,000 times the mass of the Sun, near the center of the Milky Way. This is one of the best observations ever made of a mysterious class of objects known as “intermediate mass black holes”, thought to be the building blocks of the much larger supermassive black holes we’ve come to know and love at the centers of galaxies.

The team used two radio telescopes, the Nobeyama 45-m Radio Telescope near Nagano, and the ASTE Telescope in Chile. They observed a giant cloud of gas 15 light-years across, located just 200 light-years away from Sagittarius A*, the supermassive black hole at the center of the Milky Way.

Gas clouds are common out there in the Universe, but what makes this one, unusual is how gas is zipping around within the cloud at vastly different speeds. Only something with a massive amount of gravity could hold it together like this.

They searched for pulsars and other compact objects that could hold it together, but their calculations indicated that only an object with 100,000 times the mass of the Sun could account for the behavior of the gas in the cloud.

We know there are stellar mass black holes. They form when stars with many times the mass of our Sun run out of fuel and die in a supernova explosion, leaving behind a black hole with a few times the mass of the Sun.

And we know there are supermassive black holes, with millions or even billions of times the mass of the Sun. When they’re actively feeding, they can blast out beams of radiation that outshine their entire galaxy.

But the missing link is how these supermassive black holes could have formed. You’d expect to see mergers across the Universe, with stellar mass black holes coming together into intermediate mass black holes, these merging together, and eventually leading up to supermassive black holes.

Although stellar and supermassive black holes have been found, it’s this in-between stage that has been elusive so far.

In fact, finding an object with 100,000 times the mass of the Sun, this close to the Milky Way’s supermassive black hole is actually twice the luck. If it’s this close to the heart of the Milky Way, it could be in the process of merging, building up the mass of Sagittarius A*, which would go from 4.1 million times the mass of the Sun to… 4.2 million times the mass of the Sun at some point in the distant future.

The news is reporting that this is the first time intermediate black holes have been found, but that’s not exactly true, it’s just that this is the best direct observation ever made.